The book may be referring to raising the pitch at the end of a sentence to make it a question. Like in English, if you say:
"You are going to the store." in a normal straight pitch, it is a statement, but if you raise the last word, it becomes a question. You can do that with Japanese as well

Or it may be referring to stress or accent. In Tokyo dialect, HAshi and haSHI mean different things. One means bridge and the other, chopsticks. My wife's regional dialect really has no stress - both are hashi.